[DF] Helper to draw the operation graph

tree/dataframe/inc/ROOT/GraphNode.hxx

tree/dataframe/inc/ROOT/RArrowDS.hxx

tree/dataframe/inc/ROOT/RCsvDS.hxx

tree/dataframe/inc/ROOT/RDFActionHelpers.hxx

tree/dataframe/inc/ROOT/RDFBookedCustomColumns.hxx

tree/dataframe/inc/ROOT/RDFGraphUtils.hxx

tree/dataframe/inc/ROOT/RDFHelpers.hxx

tree/dataframe/inc/ROOT/RDFInterface.hxx

tree/dataframe/inc/ROOT/RDFInterfaceUtils.hxx

tree/dataframe/inc/ROOT/RDFNodes.hxx

tree/dataframe/inc/ROOT/RDataSource.hxx

tree/dataframe/inc/ROOT/RLazyDSImpl.hxx

tree/dataframe/inc/ROOT/RResultPtr.hxx

tree/dataframe/inc/ROOT/RRootDS.hxx

tree/dataframe/inc/ROOT/RSqliteDS.hxx

tree/dataframe/inc/ROOT/RTrivialDS.hxx

tree/dataframe/src/RArrowDS.cxx

tree/dataframe/src/RCsvDS.cxx

tree/dataframe/src/RDFGraphUtils.cxx

tree/dataframe/src/RDFInterfaceUtils.cxx